Abstract
Water quality monitoring has been widely used as an early warning approach in managing water resources. In arid zones, severe freshwater scarcity is threatening the sustainability of the drinking water supply and causing huge stress on water demand. Groundwater was studied for different pollutants in four groundwater pumping stations in Saudi Arabia in the spring, summer, autumn, and winter. The results were highly variable, but in general, the concentrations in groundwater were higher than recommended by WHO for human consumption. Total dissolved solids, nutrients, salinity, and heavy metals (Mn, Cu, Cr, and Pb) were higher than recommended for most groundwater stations. Turbidity, dissolved CO2, COD, total hardness, chloride, calcium, magnesium, phosphate, sulfate, manganese, and chromium tended to be highest in summer. A purification experiment using wheat straw beds that were inoculated with the microalgae Ulothrix sp. was carried out in 25 L containers. The microalgae-straw bed treatment removed most of the polluting components from the groundwater of the four stations collected in four seasons and the concentrations settled to acceptable levels. The significance of the study lies in the practical groundwater treatment that offers an economical and sustainable technique to purify groundwater from harmful polluting compounds.